The Caluculation of 3D Saptial Dose Distribution Around a Shielded Vaginal Cylinder with Iridium-192 Source Calculated by using Monte Carlo Code EGS4

According to our previous study on the dose distribution around a shielded vaginal cylinder with a high-intensity Ir source by using EGS4 code, the more detailed 3D-simulation model was established in this work. The results obtained by the 3D-simulation model were compared with those measured by ion chamber in previous work and evaluated by the existing treatment planning system. These results show good agreement. Furthermore, the 3D spatial dose distribution around a unit intensity Ir source was calculated at each probable position in the vaginal cylinder with 90 , 180 , 270 tungsten shield and no shield cases. Those results save as a database which could be accessed through the graphical user interface developed by IDL to display dose distributions in 1D, 2D, and 3D plot under any combination of source intensity at each position, and shielding situation. It demonstrates a prototype of the brachytherapy treatment planning system based on the Monte Carlo EGS4 code.